Metallocenes ferrocenes

C5HjMn(CO)3. Triple-decker derivatives are also known. See organomelallic compounds, metallocenes, ferrocene. 

A26. M. Rosenblum, Chemistry of the Iron Group Metallocenes Ferrocene, Rutheno-cene, Osmocene, volume 1, 1965. 

Chemistry of the iron group metallocenes Ferrocene, ruthenocencand osmocene. Part. I. John Wiley and Sons, Intcrscicnce New York 1965. 

In the class of metallocenes, ferrocene systems fulfill several prerequisites for the investigation of electronic effects32,162. Therefore, it is not surprising that ferrocenyl-substituted silicon compounds have been studied most extensively. We will concentrate on this class of compounds in the following discussion. 

Rosenblum, M. Chemistry of Iron Group Metallocenes Ferrocene, Ruthenocene, Osmocene. John Wiley New York, London, 1965. 

Introduction of another ruthenium bipyridine moiety or bridging metallocene (ferrocene, cobaltocenium) results in sensors that specifically bind chloride anions (Figure 16.15). The structural modification of the amide receptor results in a decease in cavity dimensions and significant rigidity of the macrocycle. Therefore it cannot accommodate hydrogen phosphate anions, but only much smaller CF [45, 46]. 

A26. M. Rosenblum, Chemistry of the Iron Group Metallocenes Ferrocene, Rutheno-cene, Osmocene. Wiley (Interscience), New York, 1965. Only vol. 1 published, which is an excellent introduction to the organic chemistry of ferrocene and its two congeners, but unfortunately not yet completed by the appearance of vol. 2. 

Figure 6.1 Structure of simple metallocenes. Ferrocene was the first metallocene (discovered in 1951), but the correct ii-bonded structure was not identified until 1952 (JP Collman, LS Hegebus, JR Norton and RG Finke, Principles and Applications of Organotransition Metal Chemistry, University Science Books, Sausalito, CA, p 9 (1987).

Cyclopentadienyl complexes show aromatic properties. This is the origin of the names metallocenes, ferrocene, etc. For example, the Friedel-Crafts acylation proceeds very easily. Ferrocene is acylated 3.3 x 10 times faster than benzene. The acylating reagents are the organic acid chlorides and acid anhydrides. The reaction is catalyzed by the typical Friedel-Crafts catalysts BF3, AICI3, etc. 

Other materials have been used to cationize the pol5miers. Metallocenes (ferrocene, nickelocene, and cobaltocene) have been used as cationizing agents for polystyrene and PEO (47). These cations have the advantage that they are soluble in many organic solvents and also do not have the isotopic splitting seen with Ag, which often complicates the interpretation of the MALDI spectra. 

Let us first examine these sandwich metallocenes. Ferrocene has two isoenergetic conformations eclipsed (Da symmetry) and staggered (Dsd symmetry). X-ray crystallographic and electronic diffraction studies in the gas phase indicate an eclipsed conformation as well as for ruthenocene and osmocene. The rotation... 

Many discoveries in synthesis have their own anecdotal histories, one of which—the first synthesis of an organometallic metallocene, ferrocene— is mentioned here. In 1951, the newly appointed Assistant Professor Peter L. Panson, working with an nndergraduate stndent, Thomas J. Kealy, attempted to oxidatively couple cyclopentadienyl magnesium bromide with ferric chloride (52,53). The goal was to prepare fulvalene to test the then recent proposal (54) that it would display aromatic character. Instead, a very stable orange solid was produced, which proved to be the famous ferrocene, about whose structure determination much has been written (Figure 6, (55,56,57)). 

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